Overview

This package uses OpenCV camera calibration, described here. For detailed information on the parameters produced by the calibration, see this description.

The code API listed for this package is for convenience only. This package has no supported code API.

For pinhole type cameras this package names the distortion model as plumb_bob or rational_polynomial, depending on number of parameters used. For fisheye type cameras this package uses the equidistant distortion model.

Tutorials

There are tutorials on how to run the calibration tool for monocular and stereo cameras.

Camera Calibrator Usage

To run the cameracalibrator node for a monocular camera using an 8x6 chessboard with 108mm squares:

ros2 run camera_calibration cameracalibrator --size 8x6 --square 0.108 image:=/my_camera/image camera:=/my_camera

When you click on the Save button after a succesfull calibration, the data (calibration data and images used for calibration) will be written to /tmp/calibrationdata.tar.gz.

To run the cameracalibrator node for a stereo camera:

ros2 run camera_calibration cameracalibrator --size 8x6 --square 0.108 right:=/my_stereo/right/image_raw left:=/my_stereo/left/image_raw left_camera:=/my_stereo/left right_camera:=/my_stereo/right

cameracalibrator supports the following options:

Chessboard Options:

You must specify one or more chessboards as pairs of –size and –square options.

-p PATTERN, --pattern=PATTERN

calibration pattern to detect - ‘chessboard’, ‘circles’, ‘acircles’

-s SIZE, --size=SIZE

chessboard size as NxM, counting interior corners (e.g. a standard chessboard is 7x7)

-q SQUARE, --square=SQUARE

chessboard square size in meters

ROS Communication Options:
--approximate=APPROXIMATE

allow specified slop (in seconds) when pairing images from unsynchronized stereo cameras

--no-service-check

disable check for set_camera_info services at startup

--queue-size=QUEUE_SIZE

image queue size (default 1, set to 0 for unlimited)

Calibration Optimizer Options:
--fix-principal-point

for pinhole, fix the principal point at the image center

--fix-aspect-ratio

for pinhole, enforce focal lengths (fx, fy) are equal

--zero-tangent-dist

for pinhole, set tangential distortion coefficients (p1, p2) to zero

-k NUM_COEFFS, --k-coefficients=NUM_COEFFS

for pinhole, number of radial distortion coefficients to use (up to 6, default 2)

--fisheye-recompute-extrinsicsts

for fisheye, extrinsic will be recomputed after each iteration of intrinsic optimization

--fisheye-fix-skew

for fisheye, skew coefficient (alpha) is set to zero and stay zero

--fisheye-fix-principal-point

for fisheye,fix the principal point at the image center

--fisheye-k-coefficients=NUM_COEFFS

for fisheye, number of radial distortion coefficients to use fixing to zero the rest (up to 4, default 4)

--fisheye-check-conditions

for fisheye, the functions will check validity of condition number

--disable_calib_cb_fast_check

uses the CALIB_CB_FAST_CHECK flag for findChessboardCorners

--max-chessboard-speed=MAX_CHESSBOARD_SPEED

Do not use samples where the calibration pattern is moving faster than this speed in px/frame. Set to eg. 0.5 for rolling shutter cameras.

Unsynchronized Stereo

By default, the image_pipeline assumes that stereo cameras are triggered to capture images simultaneously, and that matching image pairs have identical timestamps. This is the ideal situation, but requires hardware support.

If your stereo pairs are not (or inexactly) synchronized, enable approximate timestamp matching --approximate=0.01 option. This permits a “slop” of 0.01s between image pairs. If you still don’t see a display window, or it is sporadically updated, try increasing the slop.

Dual Checkerboards

It is possible to use multiple size checkerboards to calibrate a camera.

To use multiple checkerboards, give multiple --size and --square options for additional boards. Make sure the boards have different dimensions, so the calibration system can tell them apart.

Camera Check

To run the command-line utility to check the calibration of a monocular camera:

ros2 run camera_calibration cameracheck --size 8x6 monocular:=/forearm image:=image_rect

To run the command-line utility to check the calibration of a stereo camera:

ros2 run camera_calibration cameracheck --size 8x6 stereo:=/wide_stereo image:=image_rect